On Thursday, August 5, 2010, Mariano Martinez Peck <marianopeck@gmail.com> wrote:
Hi. I know this is a newbie question, but there is something I don't understand about globals.
I am writing a piece of code, and I refer to "a class" that does exist. Suppose:
testSomething
   NonExistenteClass
Whem I accept the method, a popup brings saying it doesn't exist...etc. Then, I can define as global.
If I then evaluate:Â Â Smalltalk globals at: #NonExistenteClass
the key exist and it has nil as value. Perfect.
So..if I understand well, all these globals variables AND classes are stored in this globals, which is the only instance of SystemDictionary (for the moment).
Now my question is, where are nil, true, false, etc stored?
Magic in the compiler. They are also referenced in the special objects array.
I know there are only one instance of UndefinedObject, False, True, etc have only one instance...but WHERE are they stored? who keep them? They don't seem to be in SystemDictionary. Why no?
Efficiency. There are special bytecodes to push them. AFAIK Gemstone is the only Smalltalk that has them in the "SystemDictionary". Lukas
I did a "chase pointers" to nil for example, and it says "CLASS: SmalltalkImage class subclasses: UndefinedObject"
I still don't understand :(
Thanks for any hints
Mariano
-- Lukas Renggli www.lukas-renggli.ch